• If possible minimize the load on the refrigerator when the engine is not running by loading in food stuffs that are already chilled.
  
  
• Because cooling generates heat, good ventilation of the compressor compartment is essential for air cooled systems. If the temperature in the vicinity of the compressor rises above +40°C, ventilation needs to be improved to allow cool air (preferably from the bilge where the air is coolest) to enter at the bottom and the warm air to leave at the top. A few holes the size of a large coin are usually sufficient. All air-cooled Isotherm units with holding plates are equipped with a fan which speeds up the air flow.
  
• If you have chosen sea water cooled Isotherm SP or Magnum model, high temperature inside the boat is immaterial.
  
  
• When the refrigerator is not in use - even for a short period - always leave the door or lid slightly open to avoid unpleasant odours.
  
  
• The condensation drain in the box should always be closed when the refrigerator is in operation otherwise the heavier cold air will run out at the bottom to be replaced by lighter warm damp air from the boat.
  
  
• It is uneconomical to turn off the refrigerator during the night. In addition to an increase in average power consumption when it is started up again, it is also harmful for the food.
  

Isotherm and ASU's advantages over other refrigerators

1. Continually senses current refrigeration requirements and level of power available onboard.

2. Builds up a supply of cooling energy in the cold-holding plate when a surplus of power is available.

3. Takes advantage first and foremost of the cooling energy already stored instead of consuming battery power.

4. Recognises the difference between various power sources and regulates the system accordingly:

• When the engine is running and a large power surplus is generated under the 5-10 minutes it takes to leave or enter harbour, Isotherm ASU goes into turbo-charger mode to take full advantage of the short power surge.
  
  
• If a solar panel or shore-powered battery charger is producing the charge, this is often of low power but is available for a long period. Isotherm ASU registers the difference and allows the compressor (both compressors in TWIN) to run at exactly the correct speed so that batteries and other power-consuming equipment have first priority, but still charges the cold-holding plate somewhat slower so that the temperature in the box does not become too cold. If the solar panel is in shadow for a while, Isotherm then eases off and reduces compressor speed accordingly.
  

7. Isotherm ASU adjusts itself automatically to suit you refrigeration requirements. Should you load a large amount of warm food into the fridge at the same time, or leave the door open by mistake, the ASU system increases refrigeration capacity only enough to cool the food to a level so that it will not be spoiled.

6. Isotherm ASU doesn't dither about! Should the level of power available or refrigeration requirements change, the system first waits 30 seconds to see if the change is stable. It then determines what action is required before carrying out its task. The ASU function is also programmed for a fixed shortest running time and shortest stand-still time so that it doesn't start and stop unnecessarily thereby reducing its high efficiency factor.

7. An Isotherm ASU system continually adjusts itself to current surroundings. Whether supplied together with a compressor unit to be fitted in a bilge-cooled space on a boat used in Northern waters, or another in Dubai where it will be installed in a hot engine room, the same ASU system senses the difference. It then regulates the speed of the cooling fan or sea water pump to exactly the level required to remove the heat generated by the compressor. This is important as the sound level of the compressors are so low that even the slight amount of noise made by the fan or pump could be heard.

8. Isotherm ASU has low-voltage cut-off and reverse polarity protection, runs on both 12 and 24 volt and has full radio interference suppression.